I've recently come across a sentence in an essay I proofread that went something like "Focusing on these experimental and statistical strategies." I thought it wasn't really a sentence and suggested sth. like "I will now focus on ...", "Now I focus on ..." or "We shall now focus on ...".
Now I've stumbled across this sentence starting a paragraph (it's not a heading or something like that) in a British textbook (Hogg & Vaughan, 2013: Social Psychology):
Muzafer Sherif (1936) explicitly linking this convergence effect to the development of group norms.
Is this some participle use I've never heard of to introduce a topic or something like that?